This invention relates generally to closure caps for bottles and containers and in particular to closure concepts referred to as positive-on closures which are child-resistant by their arrangement and their nature of engagement with the container spout. Bottles and containers which contain dangerous or harmful materials represent a serious risk to small children and infants. These materials may include such items as cleaning solutions, medicines, caustic chemicals and poisons such as herbicides and insecticides. These types of material are frequently found in the home, in such places as basements, cupboards, cabinets and unfortunately, simply sitting out on floors and counters. Even with one child, it is very difficult to control that child's activities every minute of every day, and the searching, inquisitive nature of children all too frequently brings the child into contact with these types of material containers. Consequently, there is a critical need to adapt such containers with closures which cannot be defeated by small children and infants.
A wide variety of child-resistant safety closures are known to exist, and although each may afford certain improvements, none are believed to anticipate the present invention. Many closures include a type of cap-to-spout interlock which requires some type of deformation of the cap while unscrewing the cap from the spout in order to defeat the interlocking engagement. However, the specific details and characteristics of these types of closures are critical, and it is not believed that the optimal combination of features has yet been provided.
Prior closure concepts which may be relevant to the present invention are disclosed in the following listed patents.
______________________________________ U.S. Pat. No. Patentee Issue Date ______________________________________ 3,941,268 Owens et al. 3/02/76 4,117,945 Mumford 10/03/78 3,944,101 Landen et al. 3/16/76 ______________________________________
Owens et al. discloses a safety closure and container wherein a single walled cap provided with both internal threads and a pair of internal locking lugs is arranged to threadedly fit over a container spout. Associated with the spout are two camming projections, 180.degree. apart. The locking lugs have a sufficient axial height so that when the cap is fully tightened onto the spout, two separate squeezing actions are required in order to disengage the lugs from the projections so that the cap may be removed from the spout.
Mumford discloses a double side wall child-resistant safety closure wherein the inner side wall is internally threaded and the outer side wall includes two locking ribs. These ribs are arranged to interlock with shoulder segments disposed at the base of the spout of the corresponding container. This patent specifically refers to and discusses the foregoing Owens et al. patent and focuses on the benefits to be afforded by the double side wall construction. In virtually all other respects, these two patent disclosures are quite similar.
Landen et al. discloses a safety closure which includes upraised sawteeth around the base of the container spout and a continuous inner circumference of matching sawteeth on the lower interior edge of the corresponding cap. The surrounding body of the cap is configured for deformation as the cap is threaded onto the spout. These two sets or series of sawteeth have a ratchet-like design and are able to engage one another almost immediately upon receipt by the spout of that first thread of the cap. As the threaded advancement of the cap onto the spout continues, downward axial pressure is applied on the engaged series of sawteeth and this pressure increases until it reaches a relatively high force level. Removal of the cap is then effected by applying an uplifting force on the cap which is sufficient to overcome the downward axial pressure. This uplifting force draws the sawteeth out of engagement and while out of engagement, the cap is unscrewed from the spout. In one arrangement, the upraised sawteeth disposed around the spout are arranged into two series which are approximately 180.degree. apart but offset by the space of one half tooth so that engagement occurs in an alternating manner, every one half tooth of turning.
What is not provided by these patent disclosures is a combination of those benefits provided by the double side wall design and the half tooth offset ratchet design while still incorporating the convenience for adults of being able to easily remove the closure cap from the spout. In the disclosed arrangements of Owens et al. and Mumford, there is very little, if any, control of the engagement of the ribs and shoulder segments relative to the threaded receipt of the cap by the spout. In this regard, there is no interlocking engagement until the cap is almost fully threaded onto the spout. Thus, there is not afforded by these designs a positive-on arrangement wherein the closure is locked into position on the spout even when applied with insufficient torque to fully tighten the cap onto the spout.
Landen et al. attempts to overcome the foregoing shortcomings by its convoluted cap design wherein ratchet tooth engagement occurs almost at once and is maintained with the engagement of the first thread of the cap by the spout. Thereafter, as the cap advances onto the spout, the downward axial force pressing the two sets of ratchet teeth together increases until full threaded engagement is achieved. The result is a very tight and forceful safety closure fit. While this particular arrangement may achieve its one objective of being "child-resistant," its design introduces another problem. This other problem is that the removal of the cap becomes quite difficult for certain elderly persons and others who may suffer from an arthritic condition. These types of persons do not have the manual dexterity required to deal with this type of safety closure. This particular design concept relies primarily on strength in order to make it child-resistant in that an excessive amount of force is necessitated in order to remove the cap. However, it is also known that safety closures may be made child-resistant by necessitating an intricate sequence of removal steps so that mental capacity is the determinant and not physical strength.
With closure concepts of the type wherein the cap must be distorted, such as making it elliptical, in order to disengage the locking ribs from the shoulder or to disengage one set of ratchet teeth from a mating set, there is a need to know where to grasp or compress the cap so that the distortion is effective. However, certain disclosures such as that of the Mumford patent refer to the benefits of having the interlocking members "inaccessible and unobservably secluded within the interior confines of the closure." Consequently, there is no exterior indication of where to compress the outer wall and it is believed to be an improvement to provide some means of identification of these compression points. Although it might be argued that exterior identification aids the child, it must be noted that the children are small and not likely to be able to ascertain for what the identification is intended, especially if surface texturing or raised portions are used instead of descriptive words.
The present invention provides a variety of advantages over prior art devices while at the same time incorporating in a novel manner certain beneficial aspects of these prior devices. The resultant combination is a safety closure which serves the ends of adult users, including those with ailments or minor disabilities such as arthritic conditions, while maintaining the closure as "child-resistant" as will be understood by the following descriptions.